My kindle was lost or stolen (knowing me, probably lost). I got a new one and deregistered the old one. This has led to a small problem.

I use Calibre to manage my library. I've found that I can't change the title on my kindle with files that have DRM. This was a problem, because I'm a fan of mystery books, a genre where it's common to have a series about the same character, and I wanted to insert the series name and number (e.g., Poirot #4) before the title, so that I could see on my kindle which book was next in the series.

Therefore, my practice was to de-DRM AZW files, make the changes I wanted on Calibre, then (re-)upload to the kindle.

I've run into a problem: a book I had preordered several months ago was just published, and it seems it has the PID of my old kindle rather than my new one. Does anyone know where I might find the serial number of my old kindle hidden away somewhere?